This invention relates to a carbon dioxide oxirane copolymer and to a process for the preparation of such a copolymer.
Copolymers of oxiranes and carbon dioxide are useful in elastomers, adhesives and in films.
Inoue et al., Applied Polymer Symposium No. 26, pp. 257-267, John Wiley and Sons, Inc. (1975), disclose the copolymerization of an epoxide with carbon dioxide using organometallic catalyst systems under mild conditions, that is from atmospheric pressure to 50 atmospheres and from about 20.degree. C. to 50.degree. C. The catalyst is a mixture of a dialkyl zinc with a compound with two active hydrogens, for example, water, primary amines, dihydric phenols, aromatic dicarboxylic acids or aromatic hydroxy carboxylic acids. Other organometallic catalyst systems include dialkyl zinc coupled with sulfur, acetone, nitromethane and acetaldehyde.
Inoue et al., U.S. Pat. Nos. 3,585,168; 3,900,424; and 3,953,168, disclose a catalyst composition useful in the preparation of copolymers from carbon dioxide and oxiranes wherein the catalyst composition comprises the reaction product of (a) an organometallic compound having the general formula R'.sub.n M, wherein n is an integer, at least one R' is an alkyl group, an alicyclic group, or halogen or hydroxy or alkoxy radicals, or hydrogen, the remaining R' groups are alkyl groups, alicyclic groups, alkaryl groups, aralkyl groups, aryl groups, or halogen or hydroxy or alkoxy radicals, and M is a metal of group II or group III of the Periodic Table; (b) a co-catalyst component which is sulfur or a compound containing active hydrogen atoms; and (c) carbon dioxide.
Haynes, U.S. Pat. No. 3,699,079, discloses a process for copolymerizing one or more diepoxide compounds with carbon dioxide in the presence of a catalytic amount of a composite catalyst comprising an organometallic compound of magnesium, zinc, or cadmium, and one or more compounds from the group of polar organic nitro-nitroso, azooxy, amine, thiol, and sulfoxide compounds and water.
The catalysts used in the processes described hereinbefore have significant disadvantages. These catalysts are expensive to prepare, sensitive to air, and pyrophoric.
What is needed is a process for the copolymerization of carbon dioxide and an oxirane in which the catalyst is less expensive than the prior art catalysts, which is relatively stable when exposed to air and which is not pyrophoric.